The present invention relates to an information recording and reproducing apparatus, which uses a recording medium which stores information by a reversed magnetic domain on a vertical magnetic recording film formed on a surface of a substrate, records information by forming a reversed magnetic domain in the recording medium, and reproduces information by detecting magnetic leakage flux from the recording medium, and an induction type thin film magnetic head mounted thereon.
The miniaturization of the bit length and truck size of a record bit has been enhanced with the high densification of recording of a magnetic disk unit. While a recording area of an in-plane magnetic recording medium is miniaturized, the demagnetization by heat magnetic relaxation is posing a large problem, and hence, investigation of the high densification by the conversion of a recording method is accelerating. Herein, vertical magnetic recording recently attracts a lot of attention as a next-generation recording method since it has such theoretical advantages for the high densification that heat magnetic relaxation cannot easily happen since a comparatively thick recording medium can be used, and that record magnetization is stabilized as recording density is increased.
As one of the vertical magnetic recording methods, for example, as mentioned in Nikkei electronics, No. 734, Jan. 11(1999), pp. 35-42, there is a method of recording information by heating an amorphous optical magnetic medium by irradiating the medium with light, and forming a reversed magnetic domain, and reproducing information by detecting magnetic flux leaked from the magnetic domain by using a reproducing head such as a GMR (Giant Magneto Resistance) head (a first conventional example). This first conventional example has such advantages that it is possible to miniaturize an apparatus since it is possible to arrange both an optical head and an magnetic head in one side of a recording medium according to the head using this technology since the head where an SIL (Solid Immersion Lens) where a coil for a magnetic field modulation that generates a magnetic field for record is formed in a central part of a bottom face of a floating slider in a rear end part of which a GMR is formed is used, or that the flexibility of film configuration of the recording medium increases since it becomes unnecessary for the recording medium to have a light transmission in a wavelength band of a light source. As for a shape of a recording medium, a card-like shape or a disk-like shape is general geometry. Furthermore, Japanese Patent Laid-Open No. 5-54422 (a second conventional example 2) discloses an example that all of an optical waveguide layer in which a laser diode and a photo diode, and a Fresnel lens and a beam splitter are formed, and a magnetic head which is near the Fresnel lens and includes a magnetic core and a magnetic coil are installed on a face of the floating slider that opposes the medium.
In the above-described first conventional example, a recording head using an SIL and a reproducing head such as a GMR are installed in different locations. In a common magnetic recording apparatus, a floating slider is attached at the tip of a swing arm rotating with centering a certain point, and the head is made to access to a predetermined information track. Therefore, in an outer peripheral part of a record disk, some discrepancy arises in a central line of the floating slider, and a tangential direction of the information track. Then, in the case that the distance between the recording head and reproducing head is large as the first conventional example, there arises a problem that an information track, on which the recording head is performing recording, and an information track from which the reproducing head performs reproduction are different tracks. In order to make the recording head and reproducing head approach, although the miniaturization of the recording head using an SIL is indispensable, the first conventional example has an issue that the shrinkage of the recording head is difficult since an area of at least 10 xcexcm or more which makes light penetrate is required for the bottom face of the SIL and the magnetic coil is large. In addition, since the magnetic coil is large, there is also another issue that an operating speed is slow and a recording speed is slow as a result. Furthermore, since a spin valve type magnetic sensor used for reproduction had a rectangle shape nevertheless the geometry of a bit recorded was a crescent shape since a circular optical spot condensed with a lens was used as irradiation light, there was also still another problem that resolution greatly decreases at the time of reproduction.
In addition, in the second conventional example, a location of an optical spot condensed by the Fresnel lens and a location where a magnetic field is applied by the magnetic coil are separated. In the case of such structure, even if an area heated by the optical spot was small, temperature distribution spread by heat conduction as it separates from the optical spot, and the temperature distribution spread in a magnetic field application area, and hence, there was a problem that it was difficult to record a small record bit.
An light induction type thin film magnetic recording head according to the present invention comprises an angular U-shaped magnetic core having a gap on a face opposing a recording medium to be recorded, a coil generating magnetic flux in the direction perpendicular to a face of the recording medium so that a magnetic core may be surrounded, and an optical waveguide part near the magnetic core following the gap, radiates light on the recording medium by the optical waveguide part, and applies magnetic flux, generated by magnetic flux generating means, by the magnetic core. According to this configuration, since an irradiation location of light with power required for recording and a location of applied magnetic flux overlap or approaches appositionally on a recording medium, it is possible to realize magnetic domain recording in high-density and high-speed. The optical waveguide part may be constituted inside a magnetic circuit having a magnetic core, or may be provided near a magnetic core outside a magnetic circuit. A minute recording magnetic domain can be formed by provision near the magnetic circuit.
In a specific light induction type thin film magnetic recording head according to the present invention, in an induction type thin film magnetic head comprising a lower magnetic core formed on a substrate, an upper magnetic core whose front end part is connected to the lower magnetic core through a magnetic gap film and whose rear end part is directly connected to the lower magnetic core with a back contact part formed of a magnetic substance, and an insulating layer formed between the upper magnetic core and the lower magnetic core, an optically transparent waveguide part whose width is smaller than the width of the upper magnetic core and whose thickness is thinner than the thickness of the upper magnetic core is buried in the upper magnetic core, and a coil which generates magnetic flux in a magnetic circuit composed of the upper magnetic core, the lower magnetic core, the magnetic gap and the back contact part is formed around the back contact part. Furthermore, in a record/reproduction separate type magnetic recording and reproducing head including the above-described light induction type thin film magnetic recording head, a magnetic sensor that has the stacked configuration of a soft magnetic free layer/a non-magnetic interlayer/a ferromagnetic fixed layer, has a spin valve film or a tunnel junction film where magnetization to a magnetic field which the above-described ferromagnetic fixed layer should sense is fixed, and generates a magnetoresistance effect by a relative angle with the magnetization of the above-described ferromagnetic fixed layer changing by the magnetization of the above-described soft magnetic free layer rotating according to an external magnetic field, and magnetic shields arranged above and below the above-described magnetic sensor, the magnetic shield formed on the upper part of the above-described magnetic sensor serves as a lower magnetic pole of the above-described light induction type thin film magnetic recording head. Owing to these, it becomes possible to perform installation with making locations of an optical irradiation part in the upper magnetic pole, which performs recording operation, and the magnetic sensor extremely approach. In addition, since it is possible to use a part whose cross sectional geometry is a rectangle as the optical waveguide part, it is possible to make the geometry of a record bit rectangular. Furthermore, since the magnetic head can be miniaturized to at least the same extent as a thin film magnetic head put in practical use up to now, it becomes possible to increase recording speed similar to that of a conventional magnetic head.
Moreover, in the above-described light induction type thin film magnetic recording head, a transparent optical waveguide having the geometry of width and thickness gradually becoming large toward a rear end part from a front end part of the upper magnetic core is provided between the upper magnetic core and magnetic gap film to make optical power, combined with the optical waveguide, efficiently radiated on a face of a medium.
Alternatively, the above-described optical waveguide is formed in the upper part of the upper magnetic core, furthermore, an optically transparent optical waveguide having the geometry of width and thickness becoming gradually large toward a rear end part from a front end part of the upper magnetic core is provided on the upper part of the upper magnetic core, a coil generating magnetic flux in a magnetic circuit including the upper magnetic core, a lower magnetic core, a magnetic gap, and a back contact part is arranged around the above-described back contact part, moreover, a magnetic shield formed on the upper part of the magnetic sensor used for reproduction serving as a lower magnetic pole of the above-described light induction type thin film magnetic recording head makes it possible to perform installation with making the optical irradiation part, buried in the upper magnetic pole which performs recording operation, and a magnetic sensor extremely approach, and it is possible not only to increase recording speed similar to that of a conventional magnetic head by making the geometry of a record bit rectangular, but also to make optical power, combined with the optical waveguide, efficiently radiated on a face of a medium.
Alternatively, the above-described optical waveguide is formed inside the insulating layer, furthermore, an optically transparent optical waveguide having the geometry of width and thickness becoming gradually large toward a rear end part from a front end part of the upper magnetic core is provided inside the insulating layer, a coil generating magnetic flux in a magnetic circuit including the upper magnetic core, a lower magnetic core, a magnetic gap, and a back contact part is arranged around the above-described back contact part, furthermore, a magnetic shield formed on the upper part of the magnetic sensor used for reproduction serving as a lower magnetic pole of the above-described light induction type thin film magnetic recording head makes it possible to perform installation with making the optical irradiation part, buried in the upper magnetic pole which performs recording operation, and a magnetic sensor extremely approach, and it is possible not only to increase recording speed similar to that of a conventional magnetic head by making the geometry of a record bit rectangular, but also to make optical power, combined with the optical waveguide, efficiently radiated on a face of a medium.
Furthermore, in the above-described light induction type thin film magnetic recording head, by forming an optically transparent optical waveguide, having the geometry whose width and thickness become gradually large toward a rear end part from a front end part of an upper magnetic core, between the upper magnetic core and a magnetic gap film with a photosensitive resin or a mixture including a photosensitive resin, and furthermore, in the above-described light induction type thin film magnetic recording head, by an optically transparent optical waveguide, having the geometry whose width and thickness become gradually large toward a rear end part from a front end part of an upper magnetic core, forming between the upper magnetic core and a magnetic gap film with a resin, which is soluble in a chemical developer for photoresist, or a mixture including the resin, the above-described tapered structure can be easily formed by using a conventional photolithography process.
Moreover, in the above-described magnetic record and reproduction head formed by using the above-described optical waveguide material, by making the resin curing temperature of the above-described optical waveguide material be temperature lower than the temperature at which the magnetization fixation of a ferromagnetic magnetization fixed layer included in a spin valve magnetic sensor of the magnetic recording and reproducing head is coerced, it is made not to disturb the direction of magnetization of the spin valve magnetic sensor even if the above-described light induction type thin film magnetic recording head is formed after the production of the spin valve magnetic sensor.
In addition, if the above-described magnetic recording and reproducing head and the magnetic recording medium that keeps information by a reversed magnetic domain formed on a surface are used, it is possible to constitute a magnetic recording and reproducing apparatus that can perform super-high density and high-speed record and reproduction.
Thus, according to the present invention, it becomes possible to perform installation with making locations of an optical irradiation part inside an upper magnetic pole which performs recording operation, and a magnetic sensor extremely approach, and, since it is possible to use what has cross-sectional geometry that is a rectangle as an optical waveguide part, it is possible to make the geometry of a record bit a rectangle. In addition, since the magnetic head can be miniaturized to at least the same extent as a thin film magnetic head put in practical use up to now, it becomes possible to increase recording speed similar to that of a conventional magnetic head.